Electromagnetic relay



1 July 15, 1958 A. J. LEWUS 5 5 ELECTROMAGNETIC RELAY Filed Sept. 24,1954 IN VEN TOR. Alexander J Len us M Qhw/ waited rates Patent @ificeastest? Patented July 15, 1258 ELECTRUMAGNEHC RELAY Alexander .1. Lewus,Cicero, Ill.

Application September 24, 1954, Serial No. 458,241

Claims. (Cl. 317-176) The present invention relates to electromagneticrelays and more particularly to such relays of the current responsive ormarginal type of the character disclosed in U. S. Patent No. 2,547,131,granted on April 3, 1951 to Alexander I. Lewus, that are especiallysuited for use in the control circuits of single-phase induction motorsof the split-phase or capacitor type.

It is a general object of the present invention to provide anelectromagnetic relay of the current-responsive or marginal type thatembodies an improved and simplified arrangement for adjusting themagnetic reluctance of the magnetic circuit thereof so as to accommodateready adjustment of the characteristics of the relay to match thecharacteristics of a wide range of induction motors of the split-phaseor capacitor type.

Another object of the invention is to provide in an electromagneticrelay of the type noted, an improved arrangement for preventing chatterof the armature with respect to the cooperating pole piece when theassociated winding is energized with an alternating current.

Further features of the invention pertain to the particular arrangementof the elements of the electromagnetic relay, whereby the above-outlinedand additional operating features thereof are attained.

The invention, both as to its organization and method of operation,together with further objects and advantages thereof, will best beunderstood by reference to the following specification, taken inconnection with the accompanying drawing, in which:

Figure 1 is a vertical sectional view of an electromagnetic relayembodying the present invention;

Fig. 2 is an enlarged fragmentary vertical sectional view of the centralportion of the relay shown in Fig. 1; and

Fig. 3 is an enlarged plan view of the fragmentary central portion ofthe relay as shown in Fig. 2.

Referring to the drawing, the electromagnetic relay there illustratedand embodying the features of the present invention comprises asupporting plate 11 formed of insulating material, such, for example, asBakelite, and a substantially Z-shaped field element 12 formed ofmagnetic material and provided with a body 13 terminating in twooppositely directed arms 14 and 15. In the arrangement, the arm 14extend forwardly with respect to the adjacent lower end of the body 13,and the arm 15 extends rearwardly with respect to the adjacent upper endof the body 13. The arm 14 is suitably secured to the adjacent uppersurface of the supporting plate 11 by an arrangement including aplurality of rivet eyelets 16 extending through aligned openingsrespectively pro vided in the plate 11 and in the arm 14. Also, atubular winding spool-carrying member 17 formed of non-magneticmaterial, such, for example, as brass, is carried by the adjacent uppersurface of the arm 14 and secured in place by the eyelets 16 extending,through aligned openings provided therein. The member 17 comprises anupstanding substantially cylindrical barrel 18 disposed forwardly withrespect to the body 13 of the field element 12 and a lower substantiallyannular flange 19, the flange 19 being directly secured to the adjacentupper surface of the arm 14-, as previously noted. Preferably the barrel18, as well as the flange 19, of the member 17, has a longitudinallyextending slit 20 formed therein in order to interrupt the electricalcircuit path therearound so as to minimize eddy currents in the member17 that are induced therein when the Winding provided on the associatedwinding spool is energized with an alternating current. Also, the relay10 comprises a unitary Winding spool and supported Winding that isremovably carried by the member 17, the heads of the winding spool beingindicated at 21 and 22, and the winding being indicated at 23. The heads21 and 22 of the winding spool are formed of insulating material, such,for example, as Bakelite, and the composite winding 23 is formed ofsuitable conducting wire, such, for example, as copper or the like,individual terminals of the composite winding 23, not shown, beingsuitably insulated from each other.

Aligned openings 24 and 25 are respectively formed in the plate 11 andin the arm 14, the openings 24 and 25 being arranged in alignment withthe inner end of the hollow barrel 18, and the opening 25 being threadedand engaging the threaded exterior surface provided on the inner end ofa core element 26 projecting through the openings 2 and 25 and arrangedwithin the barrel 1.8. The core element 26 is formed of magneticmaterial and the outer end thereof comprising a pole end projectingtoward the outer end of the barrel 18; and arranged in the outer end ofthe barrel 18 is a first pole piece 27 formed of magnetic material. Thefirst pole piece 27 includes a substantially cup-shaped body 28 arrangedwithin the outer end of the barrel 18 and having an annular groove 23aformed therein that receives a cooperating annular bead 18a formed inthe barrel 18 so as to locate the first pole piece 27. More particularlythe preformed first pole piece 27 may be placed in the outer end of thebarrel 18, and the annular bead 13a may be rolled in the barrel 18 intothe annular groove 28a so as securely to fasten in place and properly tolocate the first pole piece 27. Arranged within the first pole piece 27is a second pole piece 29 formed of magnetic material and ofsubstantially rod-like form, the exterior surface of the second polepiece 29 being threaded and the inner end thereof being received in acooperating centrally disposed threaded hole 31 formed in the bottom ofthe body 28 of the first pole piece 27. The outer end of the second polepiece 21 comprises a pole end and normally terminates adjacent to theouter or pole end of the first pole piece 27, the longitudinal positionof the second pole piece 29 being adjustable with respect to the firstpole piece 27 by virtue of the cooperation between the threads providedon the exterio surface of the second pole piece 29 and the threaded hole31) provided in the body 28 of the first pole piece 27. To facilitatelongitudinal adjustment of the second pole piece 29 a slot 22a is formedin the outer end thereof that is adapted to receiver a screw driver, orthe like.

Also, arranged within the hollow first pole piece 27 and in surroundingrelation with respect to the second pole piece 29 is a shading coil 31of substantially Washerlike construction; the shading coil 31 beingsecured in place by a locknut 32 formed either of magnetic ornonmagnetic material and carried on the threaded exterior surface of thesecond pole piece 29.

it will be understood that the pole end of the core element 26 may beadjusted with respect to the adjacent ends of the pole pieces 27 and 29to accommodate adjustment of a gap provided therebetween by virtue ofthe arrangement of the engaging threads provided in the opening 25 andupon the outer surface of the inner end of the core element 26. Theinner end of the core element 26 has a slot 33 formed therein that isadapted to receive a screw driver, or the like, to facilitate theadjustment noted; and the inner end of the core element 26 also carriesa locknut 34 so that the adjusted position thereof within the barrel 18may be retained by virtue of the co operation between the locknut 34 andthe adjacent lower surface of the plate 11.

In view of the foregoing, it will be understood that a coarse adjustmentof the magnetic reluctance of the composite core of the relay it) may beeffected by appropriate adjustment of the longitudinal position of thecore element 26 toward and away from the adjacent ends of the polepieces 27 and 29, and that a fine adjustment of the magnetic reluctanceof the composite core of the relay may be efiected by appropriateadjustment of the longitudinal position of the second pole element 2?with respect to the first pole element 27. Moreover, it will beunderstood that the shading coil 31 effects the desired phase-shiftbetween the magnetic fluxes respectively traversing the annular portionof the body 28 of the first pole piece 27 and the second pole piece 29by virtue of the circumstance that the shading coil 31 surrounds onlythe second pole piece 29, and, in turn, is surrounded by the annularportion of the body 28 of the first pole piece 27; whereby both thebuild-up and the decay of the magnetic flux traversing the second polepiece 29 are retarded, while the magnetic flux traversing the annularportion of the body 23 of the first pole piece 27 follows directly themagnetomotive force of the winding 23 when energized with an alternatingcurrent.

Further, the relay It) comprises an armature 35 having a substantiallyZ-shape and including a body 36 terminating in two oppositely directedarms 37 and 38. The arm 37 projects forwardly with respect to theassociated upper end of the body 36 and cooperates with the adjacentouter end of the pole piece 27, while the arm 38 projects rearwardlyfrom the associated lower end of the body 36 and constituting a worklever. The armature 35 is formed of magnetic material and is pivotallymounted upon the upper portion of the body 13 of the field element 12somewhat above the upper end of the barrel 18 and between the arms 14and 115 of the field element 12. Specifically, a substantially centrallydisposed opening 39 is formed in the upper portion of the field element12 at the junction between the upper end of the body 13 and the arm 15,whereby two laterally spaced-apart sides 46 extend between the upper endof the body 13 and the rear extremity of the arm 15. Further, twolaterally spacedapart side notches 41 are provided in the sides 4t thatrespectively receive two laterally spaced-apart tabs, not shown,provided on the opposite sides of the armature 35 adjacent to thejunction between the body 36 and the arm 37 thereof. Thus it will beunderstood that the arrange ment, comprising the side notches 41respectively provided in the lower portions of the sides so and merginginto the opening 39 and respectively receiving the tabs, not shown,provided on the armature 35, mounts the armature 35 upon the fieldelement 12 for pivotal movements, the arm 37 of the armature 35 beingselectively movable toward and away from the pole face of the pole piece27 about the tabs, not shown, riding in the side notches 41.

The armature 35 is normally biased in its released position illustratedby an arrangement comprising a tension element or spring 42 projectingthrough the opening 39 and cooperating between the front end of the arm37 and a screw 43. More particularly, a substantially centrally disposednotch 44- is provided in the front end of the arm 37 that receives thefront end of the spring 42, the front end of the spring 42 beingarranged in the notch 44 and hooked over the lower surface of the outerend of the arm 37. The rear end of the arm is curved both rearwardly anddownwardly and terminates in a tab 45 having an opening therein in whichthe screw 43 is located, the front end of the screw having a holetherein that receives the rear end of the spring 42, and the rear end ofthe screw carrying an associated adjusting nut 46. As described above,the front end of the tension element 42; is pivotally connected to thefront end of the arm 37 in the notch 44, while the rear end of thetension element 42 is connected to the screw as. Thus it will beunderstood that when the nut 45 is rotated, the screw 4-3 is moved inthe associated opening provided in the tab 45, whereby the position ofthe front end of the screw 23 is adjusted both in the horizontal andvertical directions effecting corresponding movements of the rear end ofthe tension element 42. Accordingly, the tension element 4-2 normallybiases the armature 35 in the counterclockwise direction about itspivotal mounting; and the moment of this bias exerted by the tensionelement 42 upon the front end of the arm 37 may be selectively varied oradjusted depending upon the position of the screw 43 in the associatedopening provided in the tab 45. The movement of the bias is adjusted,both by the variation of the tension in the spring and by the variationin the elevation of the front end of the screw 43 with respect to thefront end of the arm 37. Further, a hole 37a? is provided in the arm 37and disposed above the slot 290 formed in the outer end of the secondpole piece 29 in order to accommodate a screw driver, or the like, so asto facilitate ready adjustment of the second pole piece 29, in themanner previously explained.

Further, the relay 10 comprises a stationary switch spring 47 and amovable switch spring 48, both suitably mounted upon the plate 11 andinsulated from each other. The switch springs 47 and 48 are formed ofsuitable electrical conducting material, and the movable switch spring48 possesses considerable resiliency. The switch springs 47 and 48respectively carry stationary and movable contacts 49 and 5t) that maybe formed of precious metal for the purpose of making and breaking theelectrical circuit between the switch springs 47 and 48. Also themovable switch spring 48 carries a pair of laterally spaced-apartupstanding arms 51 carrying a laterally extending pin 52 therebetweenupon which an insulating roller 53 is mounted. The roller 53 may beformed of glass, porcelain, or the like, and is readily rotatable uponthe pin 52 in order to eliminate friction therebetween. The outersurface of the roller 53 is urged by the resiliency of the movablecontact spring 48 into engagement with the adjacent lower surface of thework lever 38 of the armature 35. When the armature 35 occupies itsnormal released position illustrated, the work lever 33 engaging theouter surface of the roller 53 retains the movable switch spring 48 inits lower position so that the contacts 49 and 58 are disengaged. Whenthe armature 35 is moved into its attracted position with respect to thepole piece 27, it being pivoted in the clockwise direction, asillustrated in Fig. 1, the work lever 38 is effectively moved away fromthe pin 52 so that the outer surface of the roller 53 rolls upon thework lever 38 due to the resiliency of the movable switch spring 48,whereby the contact 5@ is moved into engagement with the contact 4-9closing the electric circuit between the switch springs 47 and 43. Whenthe armature 35 is moved into its fully attracted position. the worklever 38 disengages the adjacent surface of the roller 53, so aspositively to prevent chatter of the contacts 50 and 49. Subsequently,when the armature 35 is returned to its normal released position, asillustrated in Fig. l, the work lever 38 engaging the adjacent surfaceof the roller 53 forces the roller 53, as well as the pin 52 and themovable switch spring 48, downwardly so that the outer surface of theroller 53 rolling upon the adjacent lower surface of the work lever 38moves the movable switch spring 53 in order again to disengage themovable contact 54) from the stationary contact 49 so as again tointerrupt the electric circuit between the switch springs 47 and 48.

In view of the foregoing description of the construction and arrangementof the relay 10, it will be appreciated that the characteristics thereofmay be adjusted over a Wide range in order to match the characteristicsof a widge range of induction motors of the split-phase or capacitortype. Specifically, the magnetic reluctance of the magnetic circuit ofthe relay may be readily adjusted by a composite adjustment of thelongitudinal position of the core element 26 within the barrel 18 andthe longitudinal position of the second pole piece 29 with respect tothe first pole piece 27. Moreover, the moment that is exerted by thespring 42 upon the armature 35 may be readily adjusted by appropriatemanipulation of the nut 46 upon the screw 43. Among these variousadjustments, the alternating current traversing the winding 23 thatbrings about respective operation and release of the armature 35 may beselectively adjusted.

In view of the foregoing, it is apparent that there has been provided anelectromagnetic relay incorporating improved structure for varying thecurrent responses or marginal characteristics thereof over a wide range,thereby lending flexibility to the relay for use in the control circuitsof a wide variety of single-phase induction motors of the split-phase orcapacitor type.

While there has been described what is at present considered to be thepreferred embodiment of the invention, it will be understood thatvarious modifications may be made therein, and it is intended to coverin the appended claims all such modifications as fall within the truespirit and. scope of the invention.

' What is claimed is:

1. An electromagnetic relay comprising a magnetic field element, alongitudinally extending tubular member secured at its inner end to saidfield element, a longitudinally extending winding carried by saidtubular member in surrounding relation therewith and adapted to beenergized with an alternating current, a magnetic armature, a pivotalconnection between said armature and said field element, said armaturehaving a free end movable toward and away from the outer end of saidtubular member, means biasing the free end of said armature away fromthe outer end of said tubular member, a first longitudinally extendinghollow magnetic pole piece secured in the outer end of said tubularmember and having an outer end cooperating with the free end of saidarmature, a second longitudinally extending magnetic pole piece securedwithin said first pole piece and having an outer end cooperating withthe free end of said armature, means for selectively adjusting thelongitudinal position of said second pole piece within said first polepiece toward and away from the free end of said armature, a shading coilarranged within said first pole piece and surrounding said second polepiece in order to produce a phase-shift between the magnetic fluxes insaid pole pieces when said winding is energized so as to prevent chatterof said armature, said field element having an opening formed therein inlongitudinal alignment with said tubular member and communicating withthe inner end thereof, a longitudinally extending magnetic core elementcarried by said field element within said opening and projectinglongitudinally into said tubular member and having an outer pole enddisposed adjacent to the inner ends of said pole pieces and spacedlongitudinally therefrom by a gap positioned within said tubular memberand intermediate the ends thereof, and means for selectively adjustingthe longitudinal position of said core element in said tubular member soas selectively to adjust the length 6. of the gap between the pole endof said core element and the adjacent inner ends of said pole pieces.

2. The electromagnetic relay set forth in claim 1, wherein said firstpole piece is substantially cup-shaped, said second pole piece issubstantially rod-like, and said shading coil is substantiallywasher-like.

3. The electromagnetic relay set forth in claim 1, wherein said meansfor selectively adjusting the longitudinal position of said second polepiece within said first pole piece includes cooperating threadsrespectively provided on the inner end of said second pole piece and ina hole formed in said first pole piece.

4. The electromagnetic relay set forth in claim 1, and furthercomprising means carried by said second pole piece for securely clampingin place said shading coil.

5'. An electromagnetic relay comprising a magnetic field element, alongitudinally extending tubular member secured at its inner end to saidfield element, a longitudinally extending winding carried by saidtubular member in surrounding relation therewith and adapted to beenergized with an alternating current, a magnetic armature, a pivotalconnection between said armature and said field element, said armaturehaving a free end movable toward and away from the outer end of saidtubular member, means biasing the free end of said armature away fromthe outer end of said tubular member, a first longitudinally extendingsubstantially cup-shaped magnetic pole piece secured in the outer end ofsaid tubular member and having an outer end cooperating with the freeend of said armature, a second longitudinally extending substantiallyrod-like magnetic pole piece arranged within said first pole piece andhaving an outer end cooperating with the free end of said armature, theinner end of said second pole piece being threaded and engaging athreaded hole provided in the inner end of said first pole piece toaccommodate longitudinal adjustment of the outer end of said second polepiece within said first pole piece toward and away from the free end ofsaid armature, a shading coil arranged within said first pole piece andsurrounding said second pole piece in order to produce a phase-shiftbetween the magnetic fluxes in said pole pieces when said winding isenergized so as to prevent chatter of said armature, means including apart carried by said second pole piece for securely clamping in placesaid shading coil, said field element having an opening formed thereinin longitudinal alignment with said tubular member and communicatingwith the inner end thereof, a longitudinally extending magnetic coreelement carried by said field element within said opening and projectinglongitudinally into said tubular member and having an outer pole enddisposed adjacent to the inner ends of said pole pieces and spacedlongitudinally therefrom by a gap positioned within said tubular memberand intermediate the ends thereof, and means for selectively adjustingthe longitudinal position of said core element in said tubular member soas selectively to adjust the length of the gap between the pole end ofsaid core element and the adjacent inner ends of said pole pieces.

References Cited in the file of this patent UNITED STATES PATENTS2,318,359 Bellows May 4, 1943 2,410,320 Wasserlein Oct. 29, 19462,547,131 Lewus Apr. 3, 1951 2,735,967 Lewus Feb. 21, 1956

